For majority of companies, it usually takes minutes - unless of course, one of the automated check fails!
If the automated checks fail then there are quite a few verifications which have to happen manually depending upon your location, your credit rating, number of directors in your company, their location and their credit profiles and profile of the business (as obtained by Companies House).
And this can take time, possibly from a few days to weeks!
Tide usually doesn’t disclose the exact details of security verification process but if you can message them via in-app Help, you can get more details on the status. Based on my experience, they do help you until the issue is resolved!