First one is with the app connecting to phone after initial boot to fastboot. The workaround (kindly suggested to me) was to open ubports-installer via terminal with sudo.
In terminal, executing 'sudo /Applications/ubports-installer.app/Contents/MacOS/ubports-installer' solves this issue.

Secondly There appears to be an issue with adb pushing files after the download process. It looks like the adb has a problem with the location of the downloaded files.

On the mac, the location is at:
Users/<username>/Library/Application Support/ubports/pool

Its possible that during the adb push, adb cant find the location of the file because of the space in 'Application Support' folder (Application<space>Support).

If this is is the case, as a suggestion, could the app work within..
/Users/<username>/Documents
Or
/Users/<username>/Downloads

Below is the terminal output during attempt to push files. Any help would be appreciated, and if further details are required, please contact me, cheers

Terminal output:
info: Download complete
debug: adb shell: cat /etc/recovery.fstab
debug: Running platform tool exec cmd adb -P 5038 shell cat /etc/recovery.fstab
debug:
debug: adb shell: umount /cache
debug: Running platform tool exec cmd adb -P 5038 shell umount /cache
debug:
debug: adb shell: make_ext4fs /dev/block/platform/msm_sdcc.1/by-name/cache
debug: Running platform tool exec cmd adb -P 5038 shell make_ext4fs /dev/block/platform/msm_sdcc.1/by-name/cache
debug:
debug: adb shell: mount /cache
debug: Running platform tool exec cmd adb -P 5038 shell mount /cache
debug:
debug: adb shell: mount -a
debug: Running platform tool exec cmd adb -P 5038 shell mount -a
debug:
debug: adb shell: mkdir -p /cache/recovery
debug: Running platform tool exec cmd adb -P 5038 shell mkdir -p /cache/recovery
debug:
info: Start pusing 13 files
debug: Running platform tool exec cmd adb -P 5038 push /Users/macbookpro/Library/Application Support/ubports/pool/ubports-e5cf0885f061c9615931cf863a43f65d8590aa71027315ad71999252ce118868.tar.xz /cache/recovery/
debug: Error: Command failed: adb -P 5038 push /Users/macbookpro/Library/Application Support/ubports/pool/ubports-e5cf0885f061c9615931cf863a43f65d8590aa71027315ad71999252ce118868.tar.xz /cache/recovery/

at ChildProcess.exithandler (child_process.js:217:12)
at emitTwo (events.js:106:13)
at ChildProcess.emit (events.js:194:7)
at maybeClose (internal/child_process.js:899:16)
at Socket.<anonymous> (internal/child_process.js:342:11)
at emitOne (events.js:96:13)
at Socket.emit (events.js:191:7)
at Pipe._handle.close [as _onclose] (net.js:510:12)

error: Devices: Error: Adb push error:
error: Devices: Adb push error:
debug: Running platform tool exec cmd adb -P 5038 shell stat -t /cache/recovery//ubports-e5cf0885f061c9615931cf863a43f65d8590aa71027315ad71999252ce118868.tar.xz |awk '{print $2}'
debug:
info: Adb push, NaN% left