Stripe and Memberpress not connecting well due to possible hosting firewall

I am having trouble with Stripe payments connecting properly to Memberpress. The expected behavior is that after someone signs up for a membership with Stripe, they should be able to access the course they purchased instantly. Instead, they are put into a "Pending" status and I have to manually give them access. I have tested this several times now, not in testing mode using my own credit card for "payment". I have set up Memberpress and Stripe as they recommend. When I reached out to them, they said that it is likely due to a webhook issue. They suggested that either a software firewall or hosting filters IPs and gave me a list of IPs to ensure are not filtered. I have not heard back from Live Support, so thought I would post here to see if anyone knows how I can check this on my own.