There are no special steps for shared mailboxes. ODME doesn't distinguish between mailboxes types, ODME only migrates mail
from the existing source mailbox to the existing target mailbox. ODME does not check or migrates any additional properties/flags
both on source and target mailboxes.
All ODME needs, is connectivity via EWS and correct admin credentials with Impersonation.
If the option "use autodiscover" is checked, ODME then also needs the working autodiscover
for the SMTP address of the mailbox which is put in a plan.
So either configure autodiscover for the mailboxes or un-check Autodiscover
in ODME settings and use EWS URL instead