system.io - Securing Data on my MacBook Pro and other Apple products

Recently, my attempt to join a podcast on systeme.io, a platform built in France as I understand it, was very problematic. It was incredibly confusing, as I was repeatedly blocked from joining. It seemed to be connected through Google in some way, and presented an extensive disclosure which, if I signed it, I understood would allow access to a broad amount of information, including contacts and financial data.

I became very concerned about the platform and did not pursue joining.

My questions are whether anyone is familiar with Systeme.io and, if so:

1. Is it a reliable company?
2. Is it compatible with my Apple technology?
3. How can I best insure that it - or for that matter any other platform outside the Apple model - cannot access information and data on my Mac?

FYI, I always get apps from the App Store to minimize such risks.

Thank you for your support with this.

Patti