If you can log into one device, you should be able to log into all - it doesn't matter which device you use when accessing Collums.
The most common reasons for not being able to log in are:
Incorrect url - your url is https://xxxxxx.auth.collums.co.uk/ where xxxxxx is your clinic name. You cannot Google your log in url, it is NOT publicly available.
incorrect details entered. Please also try entering your details manually (rather than using a password manager) in case the wrong details have been saved.
Please check these 2 and let us know if you have further problems.
If you are having problems, please don't try another browser - Google Chrome is always the browser to use.