***ERROR: USER SUBROUTINE UMAT IS MISSING in Abaqus when trying to run a simulation with a multiscale material

I'm trying to run an Abaqus simulation with one multiscale material. I've followed the MSD 2022.1 user manual pp. 372-373. This is what I've done so far:

• I've modified my Abaqus job file to encompass my multicale material.
• I copied my mdsMAT.dat file into the directory where I run my job.
• In the directory of my job, I've created a file abaqus_v6.env.dat containing the variable usub_lib_dir, which points to
  [MSD_install_dir]/hwsolvers/MultiscaleDesigner/win64/plugins/abaqus/2019

When I submit my job with

abq2019 job=[Job_name] interactive

I get the following error

 ***ERROR: USER SUBROUTINE UMAT IS MISSING

I get the same error whether or not my usub_lib_dir file is called abaqus_v6.env.dat  or abaqus_v6.env. I'm running MSD 2022.1 on Win64 and Abaqus 2019 on Linux64. How can I make Abaqus recognize my MSD material?