Question about preparing CAMS auxiliary

[marujore]

Hi,
On page 49 of the User Manual
5.2.4 CAMS data:

For enabling the use of CAMS data in Sen2Like, the database must be prepared.

Note The CAMS monthly database for the Year 2020 is available here: http://185.178.85.51/CAMS/

I sucesfully used the database to run sen2like on 2020 data.
Is there any documentation that I can follow to prepare CAMS data for other Years?

Also, On page 50 one can read:
If CAMS is not configured, a default AOT value will be used.
How worse is this default AOT value in comparison to CAMS?

[ValentinaHutter]

I am downloading the data daily with cdsapi:

import os
import cdsapi

startdate = <INSERT DATE LIKE THIS "%Y-%m-%d">
target_dir = <INSERT DIR>

enddate = startdate
date = startdate + "/" + enddate

target_file = os.path.join(target_dir, "CAMS_archive_aod550_tcwv_msl_gtco3_analysis_0H_6H_12H_18H_{0}.nc".format(startdate))
    
server = cdsapi.Client()
server.retrieve(
'cams-global-atmospheric-composition-forecasts',
{
    'variable': [
        'total_aerosol_optical_depth_550nm', 'total_column_water_vapour', 'mean_sea_level_pressure', 'total_column_ozone',            
    ],
    'date': date,
    'time': [
    '00:00', '06:00', '12:00', '18:00',
    ],
    'leadtime_hour': '0',
    'type': 'analysis',
    'format': 'netcdf',        
},
target_file)