I have installed it on Umbraco Cloud:

<PackageReference Include="Umbraco.Cloud.Cms" Version="13.0.0" />
<PackageReference Include="Cogworks.Tinifier" Version="1.0.0" />

First of all: After install I can't see Tinifier as a "Sections" option in settings for a user group. If found that folder App_Plugins\Cogworks.Tinifier was not present so I copied files from https://github.com/thecogworks/Cogworks.Tinifier to it. Then I could see Tinifier as a "Sections" option in settings for a user group and added it.

But 2 problems are still there:

Problem 1) But when clicking "Tinify everything!" in the dashboard this error occurs multiple times in log file (once per image in the bakend I guess):

    Microsoft.Data.Sqlite.SqliteException (0x80004005): SQLite Error 1: 'no such column: day'.\r\n   at Microsoft.Data.Sqlite.SqliteException.ThrowExceptionForRC(Int32 rc, sqlite3 db)\r\n   at Microsoft.Data.Sqlite.SqliteCommand.PrepareAndEnumerateStatements()+MoveNext()\r\n   at Microsoft.Data.Sqlite.SqliteCommand.GetStatements()+MoveNext()\r\n   at Microsoft.Data.Sqlite.SqliteDataReader.NextResult()\r\n   at Microsoft.Data.Sqlite.SqliteCommand.ExecuteReader(CommandBehavior behavior)\r\n   at StackExchange.Profiling.Data.ProfiledDbCommand.ExecuteDbDataReader(CommandBehavior behavior) in C:\\projects\\dotnet\\src\\MiniProfiler.Shared\\Data\\ProfiledDbCommand.cs:line 201\r\n   at Umbraco.Cms.Infrastructure.Persistence.FaultHandling.RetryPolicy.ExecuteAction[TResult](Func`1 func)\r\n   at NPoco.Database.ExecuteReaderHelper(DbCommand cmd)\r\n   at NPoco.Database.ExecuteDataReader(DbCommand cmd, Boolean sync)\r\n   at NPoco.AsyncHelper.RunSync[T](Task`1 task)\r\n   at NPoco.Database.QueryImp[T](T instance, Expression`1 listExpression, Func`2 idFunc, Sql Sql, PocoData pocoData)+MoveNext()\r\n   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)\r\n   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)\r\n   at Cogworks.Tinifier.Repository.History.HistoryRepository.GetAll()\r\n   at Cogworks.Tinifier.Services.History.HistoryService.GetStatisticByDays()\r\n   at 
...

And when uploading new images no tinifying is made.

Problem 2) When opening an image in backend (i.e. https://localhost:44378/umbraco/#/media/media/edit/1250) and clicking Actions > Stats the dialog looks like:

So it seems that 1) tinifying does not work/does not happen and 2) some files are missing in App_Plugins\Cogworks.Tinifier