Just got around to trying this myself. Shardik is of course correct.
Using PureBasic 5.70 Beta 4 x86 - refuses to run on my elderly iMac with Snow Leopard 32-bit.
Part of the problem report is as follows:
Process: PureBasic [184]
Path: /Users/geoff/PureBasic-5.70b4.app/Contents/MacOS/PureBasic
Identifier: com.fantaisiesoftware.purebasicide
Version: ??? (0.1)
Code Type: X86 (Native)
Parent Process: launchd [92]
Date/Time: 2018-12-17 09:44:27.719 +0000
OS Version: Mac OS X 10.6.8 (10K549)
Report Version: 6
Interval Since Last Report: 2529172 sec
Crashes Since Last Report: 17
Per-App Interval Since Last Report: 1888449 sec
Per-App Crashes Since Last Report: 1
Anonymous UUID: BCB57E0E-983E-406B-9812-2B01025F6F1B
Exception Type: EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0x0000000000000002, 0x0000000000000000
Crashed Thread: 0
Dyld Error Message:
Symbol not found: _kSecImportExportPassphrase
Referenced from: /Users/geoff/PureBasic-5.70b4.app/Contents/MacOS/PureBasic
Expected in: /System/Library/Frameworks/Security.framework/Versions/A/Security
in /Users/geoff/PureBasic-5.70b4.app/Contents/MacOS/PureBasic
In the Help file with PB 5.70b4 the requirement page also says "MacOS X (10.6 or above)" so like website this wrongly implies it should work.
If it is the team's intention to no longer support the older versions of MacOS then I can fully respect that.
However, for me it's a great shame as I only have one Mac system - old and not much memory, bought with Snow Leopard 32-bit installed and I've no intention of changing it! Yes, I know it's not supported and so on, but it runs fast, is reliable and a pleasure to work on. PureBasic 5.62 runs perfectly and I can continue with it. The machine is only used for PureBasic and related work, not much else and internet access only rarely and with care.
I have several customers who are still using Snow Leopard. Without an additional later Mac system, I cannot verify if programs compiled with 5.70 will still execute on 10.6 or 10.7.