Learning How to Use Shapefiles in R - r

Question

I am trying to learn more about "shapefiles" and how to plot them in R. Ideally, I would like to make a "leaflet map" (interactive or static) that looks something like this: https://i.cbc.ca/1.5587407.1591305080!/fileImage/httpImage/covid-19-cases-in-the-city-of-toronto-since-may-1.jpg
For this example, I found a publicly available dataset that contains information about Canadian Postal Codes - I created a new random variable that represents "number of hockey players" in each postal code:
# download folder from here : https://www.serviceobjects.com/blog/free-zip-code-and-postal-code-database-with-geocoordinates/
#extract canadian part (CanadianPostalCodes202204) - call it "canada"
canada = read.csv("CanadianPostalCodes202204.csv")
# extract Ontario
some_prov <- canada[which(canada$PROVINCE_ABBR == "ON"), ]
# create some random variable for this example
some_prov$number_of_hockey_players = as.integer(rnorm(nrow(some_prov), 87, 10))
POSTAL_CODE CITY PROVINCE_ABBR TIME_ZONE LATITUDE LONGITUDE number_of_hockey_players
11 L7C 2T6 CALEDON EAST ON 5 43.81709 -79.81907 88
17 M1K 1W6 SCARBOROUGH ON 5 43.71187 -79.26526 98
21 N5Y 4N3 LONDON ON 5 43.02114 -81.22003 72
22 N4N 1J3 HANOVER ON 5 44.14945 -81.03273 87
24 N2M 3R9 KITCHENER ON 5 43.43482 -80.48112 99
26 L1C 0E4 BOWMANVILLE ON 5 43.92937 -78.68348 90
I know how to make a general leaflet map for this data - this looks something like this:
library(leaflet)
some_prov %>%
leaflet() %>%
addTiles() %>%
addMarkers(clusterOption=markerClusterOptions())
I would now like to make a map similar to the COVID map above. Doing some research online, it seems that making such a map might require a "shapefile", or some information that tells the map where to put the desired boundaries. For example, I found the following website that might be useful (https://www.gis-blog.com/create-a-leaflet-map-using-r/ - I changed "USA" to "CANADA"):
#load leaflet package for R
library(leaflet)
library(raster)
#arbitrary data (code from above)
canada <- getData("GADM", country="canada", level=2)
canada$number_of_hockey_players <- as.integer(rnorm(n=nrow(canada), 150, 30))
#create a color palette to fill the polygons
pal <- colorQuantile("Greens", NULL, n = 5)
#create a pop up (onClick)
polygon_popup <- paste0("<strong>Name: </strong>", canada$NAME_1, "<br>",
"<strong>Indicator: </strong>", round(canada$number_of_hockey_players,2))
#create leaflet map
map = leaflet() %>%
addProviderTiles("CartoDB.Positron") %>%
setView(-98.35, 39.7,
zoom = 4) %>%
addPolygons(data = canada,
fillColor= ~pal(number_of_hockey_players),
fillOpacity = 0.4,
weight = 2,
color = "white",
popup = polygon_popup)
map
But I am not sure if this is the best way to do things.
I think I found some publicly available shapefile over here : https://www12.statcan.gc.ca/census-recensement/2011/geo/bound-limit/bound-limit-2011-eng.cfm - but I am not sure how to correctly use these files to accomplish my goal. I am currently searching for other relevant shapefiles.
Can someone please show me how I can take this dataset that I created and make a map (interactive or static) similar to the COVID map above (with either postal code boundaries, city boundaries, etc.) ?
Thank you!