MRtrix3tissue ./configure problem

I’m trying to install MRtrix3Tissue on my 2017 MacBook Air (Mac OS 12.7.6).
I have successfully installed all the dependencies listed in the installation guide.
The problem arises when I type the command ./configure in the MRtrix3Tissue directory and get back env: python: No such file or directory. The configure file is in fact present in MRtrix3Tissue directory.

Here the complete script:

`Last login: Mon Aug 19 12:23:05 on ttys000

~ % export PATH=‘brew --prefix’/opt/qt5/bin:$PATH

~ % cd MRtrix3Tissue

MRtrix3Tissue % ls

CONTRIBUTING.md
icons
Doxyfile
install_mime_types.sh
LICENCE.txt
lib
README.md
matlab
bin
mrtrix-mime.xml
build
mrtrix-mrview.desktop
check_syntax
package_mrtrix
cmd
run_pylint
configure
run_tests
configure.log
set_path
core
share
docs
src
doxygen
testing
generate_bash_completion.py

MRtrix3Tissue % ./configure

env: python: No such file or directory`

My MacBook in booting from an external SSD drive, where I have installed the OS (due to storage space necessities).
If I boot from the built-in drive (running Mac OS 10.15), the ./configure command works but stops when it can’t find Qt moc (I believe it’s because Qt5 does not install successfully on Mac OS 10.15, requiring a more recent OS).
Can anyone help me with this issue?

Thank You.