Authentication methods when calling REST API with workflow robots

We are developing an add-on using some REST APIs(such as NewDownstreamBranch) to automate some UI operations of the BOM Transformer with workflow robot processing. Currently, when calling the REST API, we need to authenticate the workflow initiator, but we face the challenge of not having a way to obtain the user's password information. Is there a good way to obtain the password and pass it to the REST API? Would there be a way to obtain the password if it's an unsupported API? Alternatively, is there another authentication method that does not involve directly passing the password to REST API? If there is no viable method, we are considering requiring users to enter their password for this process.