You do not have an authorization to change sales activity &

What causes this issue?

On the basis of the settings in your <GL:user_master_record>user master
record</> and the user-related authorization in Customizing for Sales
Activities, you are not allowed to perform this action.

How to fix this error?

If you require this <GL:authorization>authorization</> in you user
master record, contact the person responsible for assigning
authorizations
Authorization object: 'VBKA_VKO'
Authorization field ID:
VKORG = Sales organization
VTWEG = Distribution channel
SPART = Division
VKBUR = Sales office
VKGRP = Sales group
KTAAR = Sales activity type
ACTVT = Action
Alternatively, you can obtain a user-related authorization for
performing this action. User-related authorizations are maintained in
Customizing for Sales Activities.

Error message extract from SAP system. Copyright SAP SE.