Buying a Google Workspace subscription is the easy part. What trips most people up is everything that happens after: connecting a domain you already own, proving to Google that you actually own it, and pointing your mail flow at Google’s servers instead of wherever it was going before.
The order that actually works
Domain verification has to happen before mail routing, and mail routing has to happen before you can safely remove any old email service. Doing these out of order is the single biggest source of "my email just stopped working" incidents during setup.
In practice: verify the domain first using the TXT or CNAME record Google gives you, then add the MX records pointing at Google’s mail servers, then add SPF and DKIM so outgoing mail authenticates properly, and only after all of that is confirmed working should you cancel or change your previous email service.
Where people get stuck
Almost every setup problem we see traces back to one of three things: the domain is managed somewhere other than where the person expected (a registrar versus a separate DNS host), a record was added to the wrong zone, or DNS propagation was mistaken for a broken record when it just needed more time.
None of these are complicated once you know where to look — they are just easy to miss on a first attempt.