Microsoft has been offering free training online for the AZ-900 exam. There have been many sessions, and as they get full, new ones are being added.
Here’s the Microsoft website that lists them through May and June:
These are two half-day sessions. And at the end, you receive a free voucher to take ANY Azure exam.
So if you’ve been studying for AZ-103, AZ-300, AZ-301 or AZ-203 and haven’t booked it yet, perhaps this can help. You can attend two days of official Microsoft training on the basics, and then take the exam you want for free.