building LIGGGHTS on new mac

Hi all,

First thanks for the great resource, I have been working on this for hours before I decided to post here.

I have followed the steps of this post: https://www.cfdem.com/forums/installation-error

and think I have VTK installed and have gotten past several issues. Now when I select make auto it runs for a while which is encouraging, but gets stuck on the same errors from this post:

https://www.cfdem.com/forums/error-non-const-lvalue-reference-type-basic...

My errors are:

In file included from ../rolling_model_luding.h:48:
../math_vector.h:97:3: error: ISO C++17 does not allow 'register' storage class
specifier [-Wregister]
register double f = sqrt(vec_dot(dest, dest));
^~~~~~~~~
../math_vector.h:225:3: error: ISO C++17 does not allow 'register' storage class
specifier [-Wregister]
register double det = form_det(m);
^~~~~~~~~
../math_vector.h:380:3: error: ISO C++17 does not allow 'register' storage class
specifier [-Wregister]
register double f = m[6]*m[7]-m[5]*m[8];
^~~~~~~~~
../math_vector.h:390:3: error: ISO C++17 does not allow 'register' storage class
specifier [-Wregister]
register double det = form4_det(m);
^~~~~~~~~
In file included from ../contact_models.cpp:72:
In file included from ../contact_models.h:69:
In file included from ../style_cohesion_model.h:2:
../cohesion_model_easo_capillary_viscous.h:328:20: warning: unused variable 'v'
[-Wunused-variable]
double **v = atom->v;
^
In file included from ../contact_models.cpp:72:
In file included from ../contact_models.h:69:
In file included from ../style_cohesion_model.h:5:
../cohesion_model_washino_capillary_viscous.h:567:31: warning: private field
'mm_liquid_transfer' is not used [-Wunused-private-field]
MeshModuleLiquidTransfer *mm_liquid_transfer;
^
2 warnings and 4 errors generated.

I think it has something to do with c++17 not being supported but would appreciate some advice on how to actually change this within terminal or the makefiles?

Thanks!