Thank you Mr.KARNOS! The problem has been solved!
The client (under maintenance) has a disco_level1 license that cannot run Spaceclaim 19.1 (which is a disc_ess/disc_sta/disc_ult license)
By upgrading SC and the server license to 2021R1 it works.

Summary of the ANSYS answer: 
I believe the following to be true:
At 19.1, Discovery SpaceClaim needed:
ANSYS Discovery Essentials    disc_ess 
ANSYS Discovery Standard     disc_sta 
ANSYS Discovery Ultimate      disc_ult

At 2021 R1, Discovery SpaceClaim needed:
ANSYS Academic Associate Mechanical and CFD    aa_a  
ANSYS Academic Associate CFD    aa_a_cfd 
ANSYS Academic Research Mechanical and CFD    aa_r 
ANSYS Academic Research CFD    aa_r_cfd
ANSYS Academic Research Mechanical     aa_r_me 
ANSYS Discovery Live Student    aa_s_disc 
ANSYS Academic Teaching Mechanical and CFD     aa_t_a 
ANSYS Academic Teaching CFD     aa_t_cfd 
ANSYS Academic Teaching Mechanical    aa_t_me 
ANSYS Discovery Essentials Enterprise    disc_ess 
ANSYS Discovery Standard Enterprise    disc_sta 
ANSYS Discovery Ultimate Enterprise    disc_ult 
Discovery - Level 1     disco_level1

The license file the customer has looks to be for 2021 R1 and newer.
The license includes:  Discovery Level 1:   disco_level1
Which was added at 2021 R1.