Sure! You can implement rate limiting in the Flask route using a decorator. Here's an example using the flask-limiter library to implement rate limiting based on the number of requests per minute:

```python
from flask import Flask, send_from_directory, abort
from flask_limiter import Limiter
from flask_limiter.util import get_remote_address

app = Flask(__name__)

# Create a limiter object with the desired rate limit settings
limiter = Limiter(app, key_func=get_remote_address, default_limits=["60/minute"])

@app.route('/download/<path:filename>')
# Apply rate limiting to this route
@limiter.limit("10/minute")  # Change rate limit as desired
def download(filename):
    try:
        # Prevent directory traversal attacks
        if os.path.isabs(filename) or ".." in filename:
            abort(400)
        return send_from_directory(directory='downloads', filename=filename)
    except FileNotFoundError:
        abort(404)
```
In this example, limiter is a Limiter object that is used as a decorator to apply rate limiting to the download route. The key_func parameter specifies how to determine the key for rate limiting, in this case using the remote IP address. The default_limits parameter sets the default rate limit for all routes to "60/minute", meaning a maximum of 60 requests per minute. Additionally, the @limiter.limit decorator is used to further specify a rate limit of "10/minute" specifically for the download route. You can adjust the rate limits as desired to suit your needs.
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