When you download a file It has a date the file was stored on the server in this case we see the server file modified date
curl -i https://www.cusd80.com/cms/lib/AZ01001175/Centricity/Domain/10180/The%20Crucible%20Anchor%20Text.pdf
HTTP/1.1 200 OK
Content-Type: application/pdf
Content-Length: 6020870
Connection: keep-alive
Date: Mon, 17 Apr 2023 20:41:22 GMT
Cache-Control: private
Last-Modified: Fri, 20 Sep 2019 22:12:36 GMT
Accept-Ranges: bytes
ETag: "921b4682070d51:0"
Server: Microsoft-IIS/8.5
Strict-Transport-Security: max-age=31536000; includeSubDomains;
X-XSS-Protection: 1; mode=block
X-Powered-By: ASP.NET
Content-Security-Policy: frame-ancestors 'self' https://*.ally.ac;
X-Frame-Options: SAMEORIGIN
X-Content-Type-Options: nosniff
Vary: Accept-Encoding
X-Cache: Miss from cloudfront
Via: 1.1 64f1d594216061fb1311499e08a4ee1a.cloudfront.net (CloudFront)
X-Amz-Cf-Pop: LHR61-P4
X-Amz-Cf-Id: 0e3WxAEhhry-z_piciSaut39s-PqkiC2llRWUKETJ8P_P-Jsu5FRvA==
The time is relative to time zone so on download the local times may be hours different. Note the difference with my curl time (22:12) and OP observation of 6:12 PM (18:12)
My copy says current time for both created and mod because I simply download without a File Manager with
curl -O https://www.cusd80.com/cms/lib/AZ01001175/Centricity/Domain/10180/The%20Crucible%20Anchor%20Text.pdf
Internally the file has multiple dates but the two most commonly shown will be via file details but neither nor both have to be shown.

3 0 obj
<</CreationDate(D:20180912082112)/Creator(PDFium)/Producer(PDFium)>>
endobj
NOTE: the time inside or outside a PDF does not need to be true it can be past or future but must be not less than any 4 digits for a nominal year. However for certain tests all dates should concur for all of one or all of the other except when using update tracking, but can still be spoofed, to say modified before creation!