Migration from SEC to Central. Prepare remote update managers error

Hi everyone, I'm migrating my clients from sophos enterprise console to sophos central.
I have no problems migrating main office computers, I have problems with brench offices that have a Remote update manager.
I'm following this guide which seems pretty clear to me but it doesn't work.

https://docs.sophos.com/central/Migrator/advancedguide/en-us/central/Migrator/AdvancedGuide/concepts/Configure_remote_SUMs.html

I go to the remote update manager, open an elevated CMD and go to: c: \ program files (x86) \ sophos \ MigrationAgent
then I issue the command:
SophosMigrationAgent.exe –p "\\ sophos \ SophosUpdate \ CloudMigrationPackage"

(\\sophos is my SEC server)

I also tried to copy the folder "\\ sophos \ SophosUpdate \ CloudMigrationPackage" to "c:\CloudMigrationPackage" and then launched the command:
SophosMigrationAgent.exe –p "c: \ CloudMigrationPackage"

in any case I get this error that I am attaching to you

what am I doing wrong?