Help with Sen2cor using SNAP

After plugin sen2cor and restart SNAP, I opened sen2cor , I chose 60m resolution and click run. SNAP warning appear (as shown in the below image). When clicking OK \ Cancel, the second window below was appeared.
Please help,

Hi Rachel,

I think the problem is related with your system variables. Could you check them? They should be similar to:

On the other hand, have you installed sen2cor as described in the user manual? ([L2A-SUM]%20S2-PDGS-MPC-L2A-SUM%20[2.3.0].pdf) Does it work properly from the command line?

Hi Omar
Thank you very much for replying.
Actually, I installed according the instructions in: [L2A-SRN]
S2-PDGS-MPC-L2A-SRN [2.3.1].pdf[L2A-SRN]%20S2-PDGS-MPC-L2A-SRN%20[2.3.1].pdf
that look like the instructions in the site you mentioned.
The versions that I installed are: Anaconda2-, Sen2cor-2.3.1
As you say, maybe the problem is with the system variables.
Hopefully, that this is the problem.
Thanks again.