I have similar issues on macOS 10.14.6 . None of unity 2019 start, 2018.3 works fine.
Here is the crash log:
Process: Unity [524]
Path: /Applications/Unity/*/Unity.app/Contents/MacOS/Unity
Identifier: com.unity3d.UnityEditor5.x
Version: Unity version 2019.3.0b3 (2019.3.0b3)
Code Type: X86-64 (Native)
Parent Process: ??? [1]
Responsible: Unity [524]
User ID: 502
Date/Time: 2019-09-18 15:20:57.957 +0200
OS Version: Mac OS X 10.14.6 (18G95)
Report Version: 12
Anonymous UUID: F4C36E29-F973-2487-453B-5E723DD3D08E
Time Awake Since Boot: 310 seconds
System Integrity Protection: enabled
Crashed Thread: 0 Dispatch queue: com.apple.main-thread
Exception Type: EXC_BAD_INSTRUCTION (SIGILL)
Exception Codes: 0x0000000000000001, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY
Termination Signal: Illegal instruction: 4
Termination Reason: Namespace SIGNAL, Code 0x4
Terminating Process: exc handler [524]
Application Specific Information:
*** CFRelease() called with NULL ***
Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 com.apple.CoreFoundation 0x00007fff53612ced CFRelease + 109
1 com.unity3d.UnityEditor5.x 0x00000001113481e2 systeminfo::GetDeviceSerialNumber() + 146
2 com.unity3d.UnityEditor5.x 0x0000000111257a18 Licensing::Module::InitMachineId() + 504
3 com.unity3d.UnityEditor5.x 0x000000011125780e Licensing::Module::Initialize() + 14
4 com.unity3d.UnityEditor5.x 0x000000010ed0ff4b InternalInitializeModule_Licensing() + 75
5 com.unity3d.UnityEditor5.x 0x0000000111554db6 EditorMain(int, char const**) + 310
6 com.unity3d.UnityEditor5.x 0x00000001115553a9 main + 9
7 libdyld.dylib 0x00007fff7f59c3d5 start + 1
Thread 1:
0 libsystem_pthread.dylib 0x00007fff7f78f3f0 start_wqthread + 0
Thread 2:
0 libsystem_pthread.dylib 0x00007fff7f78f3f0 start_wqthread + 0
Thread 3:: Profiler.Dispatcher
0 libsystem_kernel.dylib 0x00007fff7f6d1266 semaphore_wait_trap + 10
1 libdispatch.dylib 0x00007fff7f54fbd9 _dispatch_sema4_wait + 16
2 libdispatch.dylib 0x00007fff7f55039f _dispatch_semaphore_wait_slow + 98
3 com.unity3d.UnityEditor5.x 0x00000001116c9728 UnityClassic::Baselib_SystemSemaphore_Acquire(UnityClassic::Baselib_SystemSemaphore_Handle) + 24
4 com.unity3d.UnityEditor5.x 0x000000010d0b4db0 Semaphore::WaitForSignal(int) + 112
5 com.unity3d.UnityEditor5.x 0x00000001102a7d03 profiling:
ispatcher::ThreadFunc(void*) + 163
6 com.unity3d.UnityEditor5.x 0x0000000110217f8c Thread::RunThreadWrapper(void*) + 1228
7 libsystem_pthread.dylib 0x00007fff7f7902eb _pthread_body + 126
8 libsystem_pthread.dylib 0x00007fff7f793249 _pthread_start + 66
9 libsystem_pthread.dylib 0x00007fff7f78f40d thread_start + 13
Thread 0 crashed with X86 Thread State (64-bit):
rax: 0x00007fff5398b52f rbx: 0x00007ffee2d038b8 rcx: 0x000000000000000f rdx: 0x0000000000000000
rdi: 0x0000000000000000 rsi: 0x00007ffee2d038c0 rbp: 0x00007ffee2d038a0 rsp: 0x00007ffee2d038a0
r8: 0x0000000000000607 r9: 0x0000000000000000 r10: 0x00007fffb5e3b60c r11: 0xffff80023157fc00
r12: 0x0000000000000024 r13: 0x00007ffee2d03928 r14: 0x0000000000000000 r15: 0x000000012400c890
rip: 0x00007fff53612ced rfl: 0x0000000000010246 cr2: 0x000000010ed585b0
Logical CPU: 0
Error Code: 0x00000000
Trap Number: 6