The following steps should enable you to build the installation bundle which is described as the hybrid approach here.

The Recoll.app application is built with Qt Creator on MacOS Big Sur, using the .pro files which were originally set up for Windows (qtgui/recoll.pro, windows/qmk/recollindex.pro, windows/qmk/librecoll.pro). Xapian is built as a static library, using its own regular build scripts, and macdeployqt is used to produce the .dmg

cd ~/Recoll
git clone https://framagit.org/medoc92/recoll
git clone https://framagit.org/medoc92/recoll-antiword antiword
cd antiword
make -f Makefile.Linux
cd ~/Recoll/recoll
cp src/common/autoconfig-mac.h to src/common/autoconfig.h
cp src/qtgui/recoll.pro.in src/qtgui/recoll.pro

If your Qt version is not 6.4.2 (quite probable), you need to edit a few files and replace the 6_4_2 string where it appears:

packaging/mac/make-recoll-dmg.sh:qcbuildloc=Qt_6_4_2_for_macOS
src/windows/qmkrecoll/recollindex.pro:  QCBUILDLOC=Qt_6_4_2_for_macOS
src/windows/qmkrecoll/recollq.pro:  QCBUILDLOC=Qt_6_4_2_for_macOS
src/qtgui/recoll.pro:  QCBUILDLOC=Qt_6_4_2_for_macOS

Start Qt Creator and load the following project files. The qmake .pro files used for building on the Mac were initially created for Windows, which is the reason for their locations.

src/windows/qmkrecoll/libxapian.pro
src/windows/qmkrecoll/librecoll.pro
src/windows/qmkrecoll/recollindex.pro
src/windows/qmkrecoll/recollq.pro
src/qtgui/recoll.pro

You need to build libxapian.pro and librecoll.pro first then the rest in any order.

This should give you a .dmg