Basic Auth. will be Removed with Business Central 2022 release wave 1 You should use AAD instead.
See more: https://docs.microsoft.com/en-us/dynamics365/business-central/dev-itpro/upgrade/deprecated-features-w1#accesskeys
If you prefer to set up an environment with basic authentication, you can skip setting up the AAD based authentication and proceed with the steps below.

To set up basic authentication, log into your tenant, and in the Search field, enter Users and then select the relevant link.
Select the user to add access for, and on the User Card page, in the Web Service Access Key field, generate a key.
Copy the generated key and use it as the password for the username.

Now that we have the username and password, we can connect and authenticate.
Use the username in combination with the Web Service Access Key to login on the mobile device.
You can create a handy barcode containing the all login information.
This way, the user will only have to scan the barcode in order to log in.
https://docs.taskletfactory.com/display/TFSK/I+want+to+Login+with+barcode

update the START.CFG file.

Setting up basic authentication

update the START.CFG file.