I'm not sure the widget can just take a time, you may need to extract the Hour and Minute and add it to an arbitrary date, then use the time slider as normal (with 15 minute display window).
So field calculate your records and make them occur on all the same day (1 Jan 2023):
//example, replace with your date field
var yourDate = Date('2023-03-01 10:36:00')
//change to any arbitrary date you want
//e.g. $feature.date
var arbitrary = Date('2023-01-01 00:00:00')
//calculate number of minutes from midnight
var minutes = Hour(yourDate) * 60 + Minute(yourDate)
//add minutes to arbitrary date (e.g. 1 Jan 2023)
var result = DateAdd(arbitrary, minutes, 'minutes')
return result
Another option is to not use the widget, and just display your times by grouped symbology per time interval. There' s an excellent blog here - https://www.esri.com/arcgis-blog/products/mapping/mapping/unwinding-the-clock-visualizing-time-with-...
This section from the blog details how to group by hour of the day:
At what time of day was the incident reported (morning, afternoon, evening)?
var t = Hour($feature.Created_Date);
When(
t >= 22 || t < 6, "Night",
t >= 6 && t < 11, "Morning",
t >= 11 && t < 13, "Midday",
t >= 13 && t < 17, "Afternoon",
t >= 17 && t < 22, "Evening",
"Invalid date" );
Your code might look something like this: (There's obviously going to be a better function to create this but it might help you for the moment)
//replace example datetime with $feature.youorDateColumn
var now = Date('2022-01-01 10:34:00')
//get minutes from midnight
var m = Hour(now) * 60 + Minute(now)
When(
t >= 0 || t < 15, "Midnight - 12:15am",
t >= 15 && t < 30, "12:15am - 12:30am",
t >= 30 && t < 45, "12:30am - 12:45am",
t >= 45 && t < 60, "12:45am - 1:00am",
t >= 60 && t < 75, "1:00am - 1:15am and so on...",
"Invalid date" );
