You can use the direct URL to get to Security Role configuration dialog.
https://<your_tenant>.crm<region_number>.dynamics.com/tools/dialogs/RoleAssignment.aspx?dType=1&oid=%7b<guid_of_your_bpf>%7d
Replace <your_tenant>, <region_number>, and <guid_of_your_bpf> with your specific values.
https://org12345678.crm.dynamics.com/Tools/ProcessControl/UnifiedProcessDesigner.aspx?id=%7bCA703773-3DB8-4936-827B-7780680939B0%7d
https://org12345678.crm.dynamics.com/Tools/dialogs/RoleAssignment.aspx?dType=1&oid=%7bCA703773-3DB8-4936-827B-7780680939B0%7d