Synonyms returning no_such_file_exception exceptin

Elasticsearch 8.15. Followed the instructions to upload synonyms file inside a zip file /dictionaries/synonyms.txt using custom bundles ( Upload custom plugins and bundles | Elasticsearch Service Documentation | Elastic). I've tried the path

"synonyms_path": "/app/config/dictionaries/synonyms.txt" also, same error.

{
"error": {
"root_cause": [
{
"type": "illegal_argument_exception",
"reason": "IOException while reading synonyms_path_path: /app/config/synonyms.txt"
}
],
"type": "illegal_argument_exception",
"reason": "IOException while reading synonyms_path_path: /app/config/synonyms.txt",
"caused_by": {
"type": "no_such_file_exception",
"reason": "/app/config/synonyms.txt"
}
},
"status": 400
}

{
"settings": {
"analysis": {
"analyzer": {
"names_analyzer": {
"tokenizer": "standard",
"filter": [
"lowercase",
"names_synonyms"
]
}
},
"filter": {
"names_synonyms": {
"type": "synonym",
"synonyms_path": "synonyms.txt",
"updateable": true
}
}
}
}
}