Cannot load EM Client email account to my IMAC

New to EM Client and have it downloaded onto my work computer. However, I have managed to add the email account to an Iphone, Ipad but for some reason cannot get it to work on an Android phone or my IMAC. It states unable to verify username or password, yet I know I am using the correct log in details as its added the account to the Ipad and Iphone.
Any help would be appreciated

If it is an iCloud account, you need to use an app password, not the account password.

If you don’t already have one, you can generate an app password if you login to the account in your web browser.