How many products can I synchronize? What is the limit and how does the cron job work (mathematically)?

How many products can the plugin synchronize via the crone job feature. I plan to add quite a lot of products and I want to know what is the limit.

This depends only on your server capabilities (hardware and bandwidth).

If you set the recurrence to 24 hours, and 20 products per request and in Cpanel you set the cron job to run every 15 minutes, you will have 24 * 4 (60/15 minutes) * 20 = 1920 products synchronised.

Experience with the number of products per request as you wish, but if you set more products per request, the cron job may crash if the server capabilities its capabilities are not too good (or any limitation is set).