Translated from English by gtranslate.io
Visit web.locusmap.app and open your user profile (top right corner). Tap Login methods:
Here you can manage the methods with which you log in to your Locus account. You can add or delete a Google, Apple, Facebook or email authentication method. You can also change the email address or password if you use email authentication.
For example, your primary Locus account uses Apple App Store authentication. But you also want to use your account on an Android device where you can't authenticate with Apple. So you add Google as a login method.
Tap the provider you want to add > re-log in to the current provider for security reasons > log in to the added provider:

If you are adding an email method, you are always prompted to verify your email by clicking the verification link sent to your mailbox. It is not possible to add a method that is already used for another Locus account.
You can change the email address or the password for the email method:
In each case, you are prompted to insert the current password. It is not possible to change the address of Google, Apple, or Facebook authentication methods.
Tap the remove button on the login method > perform security login to your primary method and confirm:
It is only possible to manage your log-in methods on the web at the moment. The option will be implemented into Locus Map apps later.