Dear @Mick,
I have shared a way to find a workaround for the functionality which doesn’t exist in Adalo now. It is purely your decision whether to use such workarounds or not; at the moment I am not aware of any ways to get Stripe customer id other than working with Stripe API directly.
If you search on the forum with the keywords “stripe customer id”, you can find some results which might be useful for you. For instance, this post: Cancel subscription stripe with update true/false user. There is a chance that your problem could be solved even without using Integromat.
Would you prefer to submit an idea or feedback about Adalo functionality, you can always do it here: https://adalo.canny.io/.
There is also a support ticket form here Submit a Support Ticket, I believe you can find the appropriate category for your request.
Just in case, here are forum community guidelines The Adalo Community Guidelines - there are some information how to use forum and community in a best way.
Wishing you all the best.
Victor