The meeting point is on the street between COREDO Muromachi 1 and COREDO Muromachi 2.
You can wait in front of COREDO Muromachi 1 Entrance shown in the photo
The nearest station is Mitsukoshimae Station which is just under the COREDO buildings. You can either use Ginza Line or Hanzomon Line to get there. Once you get to the Mitsukoshimae Station, please find the exit for COREDO.
(Please don't confuse the COREDO in Nihonbashi Station as this is a different COREDO building. The right COREDO is the one in Mitsukoshimae Station.)
You can copy and paste this to Google Maps:
〒103-0022 Tōkyō-to, Chūō-ku, Nihonbashimuromachi, 2 Chome−2−1, コレド室町