Offsite file storage that is compatible with InDesign

With all due respect, that's a pretty heavy lift you're asking for. Not an unbearable one, and one that can be lightened considerably by significant and consistent operator actions to keep things copacetic, but a heavy burden nonetheless.

Definitions are important here: maintaining access is easy, provided you have adequate resources and permissions assigned across the crew. Production throughput and scheduling can get exponentially more difficult with the size/number of documents and the length of time needed to process them. Handoffs of documents between team members will be anything but. Plus regular (and ruthless) archiving/culling of completed work will be vital.

Some things need to be synchronized on local systems. Others can reach into consistent and curated offsite locations. Some may just have to be packaged and passed as intrinsic job folders from desktop to desktop using your offsite location(s) as repository for thos materials when they're not being worked on.

So I guess what this comes down to is that we'll need a lot more information from you about what you're working on (types/sizes/placed elements), what kind(s) of production schedules you are maintaining and where your work will go when it's completed before we could give you any real insight into what will work for you.

In short, we can't so much offer a cut-and-dried solution as help you open Pandora's Box and sort what you find inside into neat and organized piles.

Hope this helps get you started,

Randy

I use Dropbox and OneDrive and both work fine.

You can use your CC subscription’s file syncing feature, or a similar cloud syncing service like Dropbox. More on CC syncing here

https://community.adobe.com/t5/indesign-discussions/do-indesign-links-work-with-adobe-cloud-multiple-users/m-p/11521959#M400070