As there is no ARM feature in Azure yet to provision an automation runas account when provisioning automation accounts, I had to code something up to do this on the fly while we’re waiting for a Uservoice article to get prioritized.
Use my script in your pipeline to automatically provision a RunAs account. Note, the account credentials you use there should not be MFA protected or it will fail to log in.
https://gitlab.com/Lieben/assortedFunctions/blob/master/New-RunAsAccount.ps1