SyntaxError: Unexpected token ':'

[fn20200323]

I'm trying to run it on the Windows 11. I was able to remove powershell script execution limitation and correct some point to index.ts.
The something like this came:

PS C:\Users<someUser>\Downloads\gmail-mbox-stats-main> npx gmail-mbox-stats mymail="<some_person>@gmail.com" mboxpath="./.mbox"
file:///C:/Users//Downloads/gmail-mbox-stats-main/src/index.ts:88
const checkFullCount = async (): Promise => {
^

SyntaxError: Unexpected token ':'
at compileSourceTextModule (node:internal/modules/esm/utils:344:16)
at ModuleLoader.importSyncForRequire (node:internal/modules/esm/loader:420:18)
at loadESMFromCJS (node:internal/modules/cjs/loader:1561:24)
at Module._compile (node:internal/modules/cjs/loader:1712:5)
at Object..js (node:internal/modules/cjs/loader:1895:10)
at Module.load (node:internal/modules/cjs/loader:1465:32)
at Function._load (node:internal/modules/cjs/loader:1282:12)
at TracingChannel.traceSync (node:diagnostics_channel:322:14)
at wrapModuleLoad (node:internal/modules/cjs/loader:235:24)
at Module.require (node:internal/modules/cjs/loader:1487:12)

Node.js v22.17.0