You could cobble together some free or cheap apps as a replacement.
Onyx, Maintenance, and Deeper are three great apps from Titanium software that verify the disk and file structure and do cleaning.
https://www.titanium-software.fr/en/
For uninstallation of associated files when you delete an app there are inexpensive apps like iTrash, AppCleaner, and AppDelete.
If you want something to protect against malware there are free/cheap alternatives. We recently talked about some of them here and here. The free versions usually won’t scan automatically in the background so you need to manually run them from time to time. (But the top ones are all more powerful than what’s in CleanMyMacX.)
Personally, I thought it was worth my money to spend $49.98 on the v.4 upgrade license last September. But if it’s a part of SetApp and you find it useful, you’re bound to find the entire list of SetApp apps are a huge bargain overall.