Hi williamews,
I presume first that you installed the plugin as Multisite, which may have caused the issue. If that’s the case, install it as a single-site plugin on a site (instead of the network activation) and that should work on any installation.
If you did that already, then perhaps you should try a conflict test. Here is an article about how to test for theme and plugin conflicts with AWPCP, which may help pinpoint the issue: https://awpcp.com/forum/faq/how-to-test-for-plugintheme-conflicts/
Report back on what you find after that.