Having both tables’ primary keys set to the same value won’t link the two tables. What you could do is define a linked record field in [Table2] linked to [Table1] and then copy-and-paste from [Table2] primary field to the {Link to Table1} field. (I hope that was coherent; this article probably explains it better.) This link-making process could be performed prior to working with the base, at which point all records created since the last time the tables were linked could be linked — which is a long-winded way of saying you can copy/paste an entire column at a time, if you wish.
If you would rather not have this be a manual task, you can automate it using Zapier or similar middleware app. IIRC, this should be a two-step Zap, meaning it can be performed even from a free Zapier account — albeit subject to monthly transaction maximums. If you decide to go that route, in the [Documentation] table of my Wardrobe Manager base you’ll find the Wardrobe Manager Zapier Guide, which provides step-by-step instructions to create an almost identical Zap. Follow those instructions but replace the table and field names with ones appropriate to your needs…
Edit: BTW, I don’t think you need worry about users seeing each other’s phone numbers. The Airtable form view is essentially a one-way flow of data towards the base — tossed in through the transom window, as it were — without the risk (or possibility) of the form querying the base.
