Hi there, Sam! thanks for getting in touch and sorry you’re running into some issues here.
Yes, you are correct that the issue is with incompatible versions. We recommend running the same versions in order to ensure that the codebases are compatible, so you will want to update to the same version across the board to resolve the issue.
If you prefer not to renew your license just yet, you might be able to log into your account and access older versions of each plugin and sync downward instead. Then again, you may be relying on newer functionality that will get lost from 3.7 down to 3.4, so tread cautiously there as well.
Does that help answer your question? Please let me know.
Cheers!
Geoff