How to use old iTunes library from external hard drive on new MacBook Air

I'm somewhat stuck with using iTunes on my new MacBook Air. I currently run iTunes on a mid-2011 iMac using a 2TB G-Drive external hard drive as the source for music files. The G-Drive contains approximately 835 gigs of iTunes files-my entire iTunes library. The setup is basically acting as a music server-the iTunes app organizes my iTunes outward facing library and the G-Drive provides the data. Works flawlessly, including having new music that I download from CDs going directly to the G-Drive for playback through iTunes. 

Regarding the media folder location of iTunes on my iMac, when I right click on any tune in the iTunes app, the location will show the G-Drive (e.g., /Volumes/ITUNES G DRIVE/Music/Grateful Dead/5_14_78 Providence Civic Center, Providence, RI (30 Trips Around The Sun-Disc 3)/30-03 Around And Around.m4a). When I check iTunes Preferences>Advanced, there is no folder location shown in the iTunes Media Folder Location. I know that iTunes is looking at the G-Drive as the iTunes Media Folder but I don't know where it's located other than on the G-Drive. 

I would like to replicate this dynamic on my new MacBook Air. I used Apple Migration Assistant to bring over files from my old computer to the new MacBook. After migration, I confirmed that iTunes app library structure (outward facing iTunes arranged by playlist, artist, genre, etc.) migrated over flawlessly. Of course, no iTunes media data were migrated as none exists on my iMac's internal hard drive. My next step involved transferring the old G-Drive data to a new G-Drive capable of connecting to the MacBook (the old G-Drive only has Firewire 800 or mini-USB connections that don't work with the new MacBook even with after market connectors). So I purchased a new USB-C 2TB G-Drive at the Apple Store, connected it to the old iMac, created an iTunes Media Folder on the new G-Drive, and downloaded a playlist to the new iTunes Media Folder to test on the new MacBook. 

To setup playback on my new MacBook, I connected the new G-Drive to the new MacBook and changed the iTunes Preferences>Advanced iTunes Media folder location to /Volume/G-DRIVE 2019/iTunes Media. When I attempt to play a song on the new MacBook (Chet Baker's You're My Thrill) that I know is in the new media folder, I get a message the "song could not be used because he original file could not be found. Would you like to locate it?" When I right click on the song that won't play, the file location shows file:///Music/Chet Baker/Let's Get Lost/03 You're My Thrill.m4a. If I locate the song on the new G-Drive, it will play and then shows its location as /Volume/G-DRIVE 2019/iTunes Media/Music/Chet Baker/Let's Get Lost/03 You're My Thrill.m4a. So, how do I get iTunes on my new MacBook' to see and use the new iTunes media folder that I created on the external hard drive as it's source for audio playback like on my old iMac?