iMac (21.5-inch, Mid 2011) 2.5 GHz Intel Corel i5 Memory 8GB 1333 MHz DDR3/ADOBE LIGHTROOM QUESTION

Just posted this in Apple forum, going to see what i can get here....

Someone remotely from Apple upgraded my system to the macOS High Sierra 10.13.6 yesterday, however

I seem to be having complications with my Adobe Lightroom now which i didn't have before.

Does anyone have this combo? My computer, the software and Adobe LR CC 2015?

I am needing help. Apple doesn't seem to know about Lightroom and vice versa.

I had a friend suggest & set this up for me in Feb. of 2012. We no longer are in contact. I got it (refurbished from Apple) solely for photography purposes.

Adobe is telling me i need to do an upgrade in software again but after researching, it looks like my computer isn't good enough anymore to do Mojave?!

LR has a newer version which i thought i was on, the Classic 8.3.1 but i guess I'm not.

Anyway, just looking to see if anyone is in the same spot I'm in. I CAN NOT afford to go out and buy a new computer because technology keeps changing.

I don't want to not be able to edit and use my computer for what I got it for.

Can anyone help or would one be willing to help me sort all this out. Im not technology savvy and all this stuff confuses me.

I can check email, take & edit a pic, google something, and do social media somewhat but thats about it. Feeling lost and frustrated here.

Thanks.