Do I need a new computer to use Indesign - My Mac is only up to Catalina

In addition to all other advice:

I know that many users successfully install newer systems on unsupported Macs by using OpenCore Legacy Patcher:

https://dortania.github.io/OpenCore-Legacy-Patcher/

In which case you should be able to use the latest InDesign versions (as has already been mentioned, the currently available InDesign versions do not support Catalina).

I personally don't have any experience with OCLP and only post it as general info which you may or may not find useful. If you want to know more, I recommend to check forums on MacRumors.com - there are several active OCLP discussions there.

You're getting good advice here.

You may be at the absolute back end of compatibility with InDesign (and other Adobe apps) running MacOS 10.15 Catalina, and if you do want to run Creative Cloud on your older system, you want to act fast. Adobe recommendations aside, I'd suggest that you may want to run CC2024 apps on your old Mac and install them quickly on your system. As Bob says, Adobe MAX opens in a week and new versions of the software will likely be introduced. Get your CC2024 apps now because they likely won't be there in a week or two.

Bill's offering relevant info too. If you're running Catalina on a Mac Mini, or on a laptop you connect to a separate monitor/keyboard/mouse, the price point to get the latest Mac Mini is as cheap as $600US. Thanks to the speed of the Thunderbolt 4/USB4 ports on the cheapest Mac Mini M4, you can run external storage at speeds as fast or faster than the internal bus speed of your old setup, provided you get a 4th generation blade-type SSD and an external enclosure tht's fully compatible with Thunderbolt 4/USB4 speeds. And even the cheapest Mac Mini today comes with 16GB of RAM for its System on a Chip (SoC) that is the practical minimum for running the latest software included in CC2025/2026.

Not to spend your money, but I'm pretty tight when it comes to spending my money on system upgrades. I was about to abandon running the Mac platform and go exclusively Windows PC before Apple announced the M4 Mac Mini. I didn't have many clients working on Mac anymore, and the price point to upgrade before that wasn't worth it to me. But the price and specifications for the new Mac Mini were so good that I bought the cheapest one and spent about $200 on external storage/backup SSDs and enclosures to continue running on the Mac platform too. 

My trusty old Intel-chipped Mac Mini is now my music jukebox and email server. And my new cheap M4 Mac Mini absolutely flies running Creative Cloud apps. It's also extended future compatibility on the Mac platform for a long time to come ... hopefully.

Hope this helps,

Randy

Unfortunately, in terms of performance both the programs and operating systems have been optimized for the most recently released computers. Every year when the new Macintosh's OS has been released Adobe keeps needing to make changes to the Creative Cloud programs in order to assure full compatibility with Apple's latest. This means that the latest versions of the apps—even though they may have been initially compatible with an earlier OS—may or may not maintain that compatibility with an older OS. It has become a constant dance between the computers and software producers to keep up with one another. That is why my feeling is that having a newer computer will at least give you a fighting chance in this battle. But, I should also point out that updating either the OS or InDesign as soon as the latest versions come out is also probably not a good idea. This is especially true for each of the latest Mac OS releases. The forums consistently show major issues running the latest versions of Creative Cloud apps with the initial Apple releases. Patches and bug fixes in both the OS and the apps usually can appear for at least a few months after an OS release. All that being said it is still a really good idea to replace a computer when it is on the edge of compatibility.

Hi @AP26534400ksyd, your Catalina setup is fully compatible with InDesign, right now it's the oldest supported OS, so you should be good. But your computer needs to have the minimum requirements in terms of RAM. 16GB is recommended and you need at least around 4.5 GB of free storage space. Do you know what your processor is? It could be that your system doesn't have the horsepower required. You can try a free trial if you aren't subscribed yet.