Capium 365 is a secure online portal designed for clients to access their accounting information, share documents, and stay connected with their accountant. Whether you're using the web version or the mobile app, logging in is quick and straightforward.
Receive the Invitation Email
Your accountant will send you an email invitation from Capium.
Open the email and click the registration link.
Set your password and complete the registration process.
Tip: If you haven’t received the invite, check your spam/junk folder or ask your accountant to resend it.
After accepting the link and setting the up the credentials.
Access the Login Page
You can also visit www.capium.com
Click Client Login and enter your login deta
Enter your registered email address and the password you created
Once logged in using your credentials, you will be prompted to enter a One-Time Password (OTP) and complete the Veriphy verification process. 
After completing the verification, you will be redirected to the main login page, where you can select Capium 365 to proceed.
Click here to How to Login into Capium 365 ? (Mobile)
Link
https://capium.freshdesk.com/a/solutions/articles/9000270039?portalId=9000044273