SSIS package fails with error "If 64-bit driver not installed, run in 32-bit mode"

if you are executing the SSIS package from job , there is an option in job configuration a checkbox "enable 32 bit".

OR

if you are executing the SSIS package from BIDS or SSDT , go to project properties=> Configuration => debugging => turn 64BitRuntime from "True" to "False" as it is set to True by default.

You are attempting to run an SSIS package from the SSISDB catalog and need it to be in 32 bit mode.

The TSQL for such would look like the following

DECLARE @execution_id bigint;
EXEC SSISDB.catalog.create_execution
    @package_name = N'Legacy_DataExport.dtsx'
,   @execution_id = @execution_id OUTPUT
,   @folder_name = N'Legacy_DataExport'
,   @project_name = N'Legacy_DataExport'
,   @use32bitruntime = True
,   @reference_id = NULL;
SELECT
    @execution_id;
DECLARE @var0 smallint = 1;
EXEC SSISDB.catalog.set_execution_parameter_value
    @execution_id
,   @object_type = 50
,   @parameter_name = N'LOGGING_LEVEL'
,   @parameter_value = @var0;
EXEC SSISDB.catalog.start_execution @execution_id;
GO

Of note is the penultimate parameter of the first EXEC where we specify @use32bitruntime = True

From the UI perspective, it looks like